Semiconductor apparatuses generally include chips or dies that are formed on a wafer and then packaged. Semiconductor apparatuses are considered to be at a wafer level when their chips or dies are still in wafer form and are at the package level after the chips or dies are packaged.
Various tests may be performed on semiconductors to ensure function, yield, quality, and reliability. A wafer level test may be performed when a semiconductor apparatus is in the wafer stage. The wafer level test may be performed using external test equipment and a probe. After the semiconductor apparatus is packaged, a package level test may be performed using external test equipment.
Although it is the norm that semiconductor apparatuses are tested using external test equipment, semiconductor apparatuses may include built-in self test circuits to increase test efficiency. The built-in self test circuits allow various tests to be performed faster and with more testing options compared with tests conducted by external test equipment.
At the package level, various tests associated with all operations of the semiconductor apparatus may be performed. However, at the wafer level, the semiconductor apparatus is limited by its number of usable pads or pins, which limit the number of signals that may be input from external test equipment.